I'm going to be that guy. I showed up knowing what Spirit told me to know on day 1. Limitations. Memory items. And familiar with the flows. Spirit gives every pilot ample time to learn and practice flows during the ground portion of training in front of a paper tiger, FMS, and touch screen trainers. Also, spirit will give you all the source material (and there is a lot of it) that instructors and check airman draw from. There is no need to go outside to find materials to study from. Now, if one desires to go above and beyond and purchase apps, videos, on line tutorials, and more, then have at it. But, everything you need to know to be successful in Spirits training program is provided to you by Spirit. Disclosure: I am a former Part 61 instructor, Part 135 and Part 125 pilot with no previous Part 121 experience. The training at Spirit was easier and less stressful than the training I did in Part 135. The only people in my initial class at Spirit that were stressed were those that brought it on themselves.